2004 Kawasaki ex500

I recently acquired a rolling chassis ex500 and I plan on following JoeReal's build quite closely. Right now all I have is the chassis, but I will update this thread with planned components and pictures.

I don't plan on using a BMS at first, but will manually balance cells during install and undercharge during routine use

So now some questions before I pull the trigger on purchasing everything:
1. Can I potentially have a reverse gear with this setup? If not, how difficult would that be to accomplish? I would like to reverse into my garage which is at the top of my steep driveway.
2. Has anyone had any experience with the "new old stock" chargers from ev-drives. Are they reliable? How do I go about getting it programmed for Lithium?
3. What do you think of my 3.57 gear ratio? I am hoping to get up to at least 65mph if necessary, but I doubt I will ride on the highway due to the extreme negligence of other drivers in my area.

I am trying to get this elmoto excel file to work, but I must admit it is rather confusing.

I have a very similar setup as your plan also with a very large and heavy 530 chain as that was stock on my fazer fz6-E but with the less effective Kelly controller I've clocked 68mph from 10 leaf cells with a 1:3.3 gear ratio but the chain 520 or 530 are over kill even for the petrol engine drz400 knows his stuff and I don't want to contradict him but for ease and cost I would keep the stock chain and sprockets untill they need replacing then consider down sizing a little

As a suggestion: try if possible to opt for sprockets with odd number of teeth. They last longer as the inside plate of the chain will hit every spot between the teeth instead of every other one. They also run a little quieter.